Electrical contact plug



Sept. 21, 1943. w, H. CHURCHILL ELECTRICAL CONTACT PLUG Filed Dec. 10, 1942 f Patented Sept. 21, 1943 ELECTRICAL CONTACT PLUG Wilmer H. Churchill, Saugus, Mass., assignor to United-Carr Fastener Corporation. Cambridge, Mass, a corporation of Massachusetts Application December 10, 1942, Serial No. 468,555

3 Claims.

The present invention relates to electrical contact plugs of the type commonly used in electrical discharge or thermionic tubes and aims generally to improve the construction of existing plugs of that type.

One-type of plug to whichthe invention particularly relates is called a banana shape plug and comprises a central core with a. split sheet metal cage bulged outwardly from the central core so as to make resilient contact with the sockets into which they are inserted. The plug has a portion which is embedded in the molded tube base and is preferably tubular for electrical connection with a wire within the tube. Such cores have previously been screw-machine made parts which are relatively slow and costly of manufacture and must be turned from stock of substantially larger diameter thus necessitating considerable waste of metal.

.Heretofore, similar banana type plugs have been made by attaching a cage to a stem having ahead, core and intermediate cup-shaped skirted flange. The stem .was previously made on a screw machine by turning down the end portion and then borin out the intermediate portion to form the cup-shaped flange. This involved a -relatively slow machining operation, as well as a considerable waste of metal in lost turnings, all of which added materially to the cost of'making the plug.

My present invention aims to improve the con struction of such plugs whereby the necessity for screw-machine made parts is eliminated,

. thus facilitating the manufacture of the plugs cage having its central portion in contact with substantially the entire area of the outer end of the core and the terminal ends of the fingers crimped or clenched under the flange of the tubular attaching part. According to the invention the attaching part, core and cage are formed separately on conventionalmachines designed to produce the parts quickly and economically and with a minimum waste of material.

- Referring more particularly to the drawing, the contact plug is of three-piece construction comprising an eyelet-attaching part I0, a headed core l5 and a finger cage 18, as is most clearly illustrated in Fig. 3. The attaching part is preferably in the form of a tubular eyelet It made on an eyeletting machine and has a reduced shank II and an enlarged flanged. cupped to a preferred form of the invention, the plug being illustrated as embedded in an insulating body and electrically connected to a conducting wire;

Fig. 2 is an enlarged cross-sectional view as taken on the line 2-2 of Fig. 1;

Fig. 3 is a sectional view of the parts composbase 12 at one end thereof. The reduced shank portion H is of proper length to extend through an insulating support 12, as .for example the molded base of an electrical discharge tube (not shown), and may be clenched in place and electrically receive a conducting wire l3 positioned -within the interior of the tubular shank It and secured thereto by suitable means, as for example a soldered connection it. The core part is preferably formed as an elonfgated core l5 having a rounded nose It and a head I! on the opposite end adapted to fit within the cupped flanged base 82. This part may be conveniently formed on a heading machine from a blank of wire stock substantially the diameter of the core l5. Its manufacture thus involves little or.no waste of metal and it may be more economically and rapidly produced on a coldheading machine than on a screwmachine as was the case heretofore. 1 The finger cage I8 is preferably formed from a cross-shaped blank (see Fig. 4) preferably having a solid center It and a plurality of radially extending fingers 2c. .The center portion I9 is preferably cupped to conform to the shape of the core nose It to provide a good electrical contact with substantially the entire semi-spherical end of the core. The fingers 2B extend away from the cupped portion 59 in a divergent direction for a substantial distance and then in a convergent dlrection toward their free ends, providing outwardly spaced bulges or bowed portions spaced from said core it. The terminal ended the fingers 2d are flanged outwardly, as at 2|, to

The assembled contact plug, as illustrated in Fig. 1, provides a strong eficient plug providing a good electrical conductor from the shank it of the eyelet through the core i 5 to the nose thereof which has substantial continuous contact with the central portion of the finger cage circumferentially in at least two places, as illustrated in Figs. 1 and 3. The bowed fingers being in engagement with the core it at both ends thereof provideyieldable sides for making resilient contact with the sides of the socket memher (not shown) into which the plug is inserted.

Advantages of the invention reside in the improved construction of a multiple part banana type contact plug of simple and strong construction which permits manufacture of the component parts expeditiously by rapidly operating heading machines, as distinguished from the slower screw machine.

While I have illustrated and described a preferred embodiment of my invention I do not wish to be limited thereby because the scope of I my invention is best defined by the following being flanged, said annular skirt being inturned under said head and flanged finger ends for secore shank, a plurality of outwardly bowed re-' silient fingers extending from said cupped central portion and circumferentially spaced around said core, the ends oi. said fingers being flanged, said annular skirt being inturned under said head and flanged finger ends for securing all of said parts in assembled relation.

3. An electrical contact plug comprising a tubular eyelet having a reduced shank adapted to be embedded in a support and receive an electrical conductor, said eyelet having an enlarged base beyond the support and formed with a depending annular skirt, a separate core having an elongated shank and flanged head fitting within said annular skirt and a separate contact cage formed with a cup-shaped central portion embracing and in contact with the end of said core shank, a plurality of outwardly bowed resilient fingers extending from said cupped central portion and circumferentially spaced around said core, the ends of said fingers being flanged, said annular skirt being inturned under said head and flanged finger ends for securing all of said parts in assembled relation.

WILMER H. CHURCHILL. 

